caused by the punctures of the insects, which is known under the name of honey-dew.

sex;

Each family of plant lice in spring and summer consists of individuals always wingless and of pupae; all these, however, are females, which produce living young without a previous union with the other and Bonnet, whose researches have removed all doubts upon the subject, has clearly shown that this power is exercised at least through nine generations, which are produced within the space of three months. Whilst Duvau thus obtained eleven generations in seven months, and Kyber even observed that a colony of Aphis Dianthi, brought into a constantly heated room, continued to propagate for four years, with a single impregnation of a female by a male, the young being constantly produced of the female sex. The males, of which some are winged, and others apterous in the same society, are not born until the end of the summer or autumn. They fecundate the last generation, produced by the previously born specimens, consisting of wingless females, which then deposit fecundated eggs, which remain through the winter, and produce young in the spring capable of reproduction without fresh impregnation. It is impossible in this work to enter into the numerous details relative to these insects, which have attracted so much of the attention of naturalists; I must therefore refer more particularly to the memoirs of Bonnet, Réaumur (Mém. tom. iii. mém. 9 and 11., and tom. vi. mém. 13.), De Geer (Mém. tom. iii. chap. 2 and 3.) Curtis (Observ. on Aphides, in Trans. Linn. Soc. vol. vi. Phil. Trans. 1771.), Sauvages (on Honey-dew, in Journ. de Physique, tom. i., and in his memoirs), as well as the elaborate anatomical researches of Duvau, Dutrochet, and Morrem, above referred to.

Many of the species have the body densely clothed with a white cottony secretion, either in threads or flakes; amongst these may particularly be mentioned the Aphis lanigera, or American blight* as it is termed, which infests the stems of apple trees, sometimes totally destroying them. This species belongs to the genus Lachnus Illig. Myzoxyle Blot, Eriosoma Leach, differing from Aphis in the neuration of the wings, as well as in the want of tubercles at the extremity of the body for the secretion of honey-dew. The antennæ also

* The details of the history of this species are given by Knight and Sir J. Banks in the Horticult. Trans.; by Knapp in the Journal of a Naturalist; Annales Sci. Nat., March 1831; D'Arcilly in Bull. de l'Acad. Ebboicienne du Département de l'Eure, 1834; Audouin in Ann. Soc. Ent. France, tom. v. p. 9. App.

are shorter than in the true Aphides. Other species agreeing with Lachnus lanigerus in the neuration of the wings, have the body naked and the wings in repose carried flat upon the body. I possess three small British species of this group. The very large species which Mr. Haliday has conjectured is identical with Phylloxera, found by Réaumur in the crevices of the oak, and figured by him (Mém. tom. iii. pl. 28. f. 5—14.) (Lachnus Quercus Burmeister) agrees with these in the wings being carried fat upon the body, and the body destitute of tubercles; but the apterous individuals are naked, and have the promuscis nearly three times as long as the body beneath which it is extended in repose, reaching far beyond its extremity like a tail: from the greatly magnified figures of this instrument given by Réaumur, this instrument appears evidently 4-jointed, the penultimate joint being thickened and the preceding joint being capable of great contraction. The genus Phylloxera Fonsc. differs from the preceding in having still fewer nerves in the wings (only three simple ones upon the disc of the wing), although these organs are carried flat upon the back. M. Fonscolombe has sent me a specimen of the species found by him on the Elæa angustifolia (Ann. Soc. Ent. France, 1834, p. 224.), with the expression that it certainly belongs to his genus Phylloxera; and M. V. Audouin has supplied me with both sexes of the species found on the oak. The very minute species Vacuna coccinea of Van Heyden (to whom I am indebted for specimens) has the wings similarly veined. The genera Paracletus and Forda V. H. (which I also possess from their talented describer), as well as his g. Trama, are founded upon minute species which reside in ants' nests.* (Réaumur also mentions finding Aphides in the nests of these insects.) These insects are all apterous as well as the genera Rhizobius Burm., and Atheroides Haliday. The last-named author has published some interesting observations on the habits of the species of Eriosoma in the Annals of Nat. Hist., Nov. 1838, the majority of the species of which are produced within

* I have above (p. 229. and 234.), alluded to the fondness of ants for the saccharine matter secreted by the Aphides, the place of which seems supplied in tropical climates by the more numerous species of Centrotus and allied genera.

↑ In Risso's Hist. Nat. de l'Europe Mérid., tom. v. 1826, two new genera are indicated by Leach, namely, Doralis (sp. Pini Leach, Dauci F., Ulmi Le., and Rumicis Le.) and Phalaris (sp. Cerasi Le., Absinthii Le., Salicis Le., Vitis Le., Populi Le., and Tanaceti Le.), without any characters; and a new species of Eriosoma is described under the name of E. Oleæ. I do not know the genus Adelges Vallot.

gall-like protuberances on the leaves of trees. The group, as proposed by Leach, corresponds with Latreille's 3d section of Aphis, and comprises the Aphides Gallarum Ulmi, Tremula, Xylosthei, and Gallarum Abietis, all figured by De Geer. The last-named species recedes much from the rest of the family, and approaches nearer to the Coccidæ, especially in the nearly globular form of the swollen females, which have very short legs, antennæ, and proboscis, but the setæ of the latter organ are capable of being greatly exserted.

The species of this family are greatly subject to the attacks of other insects; the larvæ of the Hemerobiidæ, the Coccinella in the larva and imago states, and the larvæ of various species of Syrphide feed upon them, and destroy vast numbers, whilst they are parasitically attacked by numerous minute Hymenoptera, belonging to the families Chalcididæ, Proctotrupidæ, Cynipidæ, and Ichneumonidæ ; indeed, one of the genera of the Adscitous Ichneumons is named Aphidius. When an Aphis has received an egg of one of these parasites, it quits its companions, and fastens itself by its ungues to the under side of a leaf, where it swells nearly into a globular form, its skin stretched out and dried up, and in a short time the perfect parasite escapes by a circular hole, the mouth of which sometimes remains like a trap door. Some of the fossorial Hymenoptera also provision their nests with Aphides (see antè, p. 195.).

The species require a careful monograph, although descriptions of detached species have been given by Curtis, Walker, Haliday, Blanchard, L. Dufour, Van Heyden, Morrem, Burmeister, and other recent authors.

The family ALEYRODIDE consists of the minute species of the genus Aleyrodes (fig. 118. 1. A. Chelidonii, magn. ; 2. ditto in repose, three times nat. size), distinguished from the Aphide by the broad, farinose, and nearly equal-sized wings, and still more by the transformations; and from the Coccidæ by both sexes being furnished with four wings in the perfect state. The head is small (fig. 118. 3.), with the eyes bipartite (fig. 118. 4.), and not emarginate, as stated by Latreille (R. An. tom. v. p. 228.) ; the antennæ are short and 6-jointed; the promuscis is short, and apparently only 2-jointed, the basal joint longest, and the last short and conical, as is also the labrum, from the extremity of which I extracted two curved setæ in one specimen (fig. 118. 4.); the collar is short and transverse; the abdomen neither

tubercled, corniculate, nor furnished with long threads at the tip; the four wings are broadly oval, nearly of equal size, covered with a white powder, the anterior having only one strong central nerve*; in repose they are carried nearly horizontally (fig. 118. 2.); the legs are short and simple; the tarsi 2-jointed, with two ungues (fig. 118. 5.). The transformations of this genus are extremely interesting, agreeing with those of the male Coccus in the scale-like form of the larva, totally unlike the imago (fig. 118. 6. after Burmeister), and in the quiescent state of the pupa covered by the skin of the larva. We are indebted to Réaumur for a minute account of the habits of this insect (Mémoires, tom. ii. mém. 7. pl. 25.), which feeds, in the larva state, on the leaves of Chelidonium majus, the cabbage, oak, &c., and of which the larvæ and pupæ are devoured by a minute Coleopterous larva, apparently from Réaumur's rough figure of the imago belonging to the Coccinellideous genus Scymnus. The type of the genus, A. Chelidonii, was regarded by Linnæus as a Tinea (Ph. T. proletella, Syst. Nat. vol. ii. p. 889.). Réaumur has given a calculation of the number of individuals produced from a single female, showing that in twelve generations the number is at least 200,000 in one year; hence, Linnæus observes, "Parit quotannis 200,000 soboles, dum 12 progenies ponant 12 ova singulæ."+ These eggs, varying in number from eight to thirty-six, are arranged around a circular space, covered with white powder, on the undersides of the leaves.

G. N. 1437. Pinicola and Aleyrodes gigantea and dubia of Stephens's Catalogue are species of the Neuropterous genus Coniopteryx.

* Burmeister has incorrectly represented them with nerves similar to those of Coccus. (Handbuch d. Ent. vol. ii. t. 2. f. 7.)

Kirby and Spence, overlooking this calculation, give 200,000 as the number of eggs produced by a single individual. (Introd. to Ent. vol. iii. p. 89.)

The section MONOMERA, comprising those species which possess but one joint in the tarsi, terminated by a single unguis (fig. 118. 12. leg of C. aceris), is composed of the single family CocCIDE*, or scale insects (fig. 118. 19. Lecanium Hesperidum ? ), one of the most anomalous tribes of insects with which we are acquainted; and which clearly proves that annulose animals may exist, which become more and more imperfect as they approach the imago state, and which in that state lose all trace of articulations in the body, as well as of articulated limbs (as in the female Cocci and Aspidioti); becoming, in fact, inert and fixed masses of animal matter, motionless and apparently senseless, and which resemble nothing more nearly than the vegetable

Anderson.

BIBLIOGR. REFER. TO THE COCCIDE.

Letters to Sir J. Banks on Cochineal Insects found at Madras, 1773, 1795. Ditto, in Asiatic Researches.

Roxburgh.

Virey.

On Chermes Lacca, in Phil. Trans. vol. lxxxi.

Rech. sur l'Insecte de la Gomme-laque, in Journal de Pharmacie, 1810.

Kerr. On Gum-lac Insects, in Phil. Trans. 1781, vol. lxx.

Breynius. Hist. Nat. Cocci radicum tinctorii, and Corrigenda, &c. to ditto, in Act.
Erudit. 1731, 1733, and in Phil. Trans. vol. xxxvii.

Burchard. Epist. de Cocco Polonico, in Act. Soc. Upsal, 1742.
Wolff. On the Polish Cochineal, in Phil. Trans. vol. liv. and lvi.
Haworth. In Trans. Ent. Soc. 1812.

Truchet. Dufour.

Traité Complet du Kermes, 8vo, p. 101. Paris, 1811. Descr. d'une n. Esp. de Coccus, in Ann. Sc. Nat. tom. ii. Réaumur. Mémoires, tom. iv.

Latreille.

Hist.

De Geer.

Linnæus.

Descr. K. ♂ de l'Orme, in Magas. Encycl. tom. ii. 1796. — Ditto, in d. Fourmis.

- Ditto, on Aleyrodes, in Magas. Encycl. 1795.

Mémoires, tom. vi. mém. 8.

Suensk Coccionell., in Sw. Trans. 1759.

Modeer. Monographia Generis Coccus, in Gothaborg. Vetensk Handl. 1778.
Dalman.

On Swed. Cocci, in Sw. Trans. 1825.

Brandt and Hamel. In Mem. Acad. Petersburgh, vol. iii. n. series.

Fonscolombe, in Ann. Soc. Ent. de France, 1834.

Bosc. Descr. du Dorthesia Characias, Journ. de Physique, tom. xxiv.

Dorthes. Observ. on ditto, in ditto, tom. xxvi.

De Berneaud, in Ann. Soc. Linn. Paris, livr. iv. 1824. (Dorthesia Delavauxii.)
Bouché, in his Naturg. d. Insecten, band 1.

Ratzeburg. On Coccus, in Der Medizinischen Zoologie, Berlin, 1833.

L. Guilding. On Margarodes, in Linn. Tr. tom. xvi.

Costa, in Atti Sci. Nat. Napoli (Bull. Ferruss., Sept. 1830), and Fauna del Regno di Napoli.

And the general works of Linnæus, Geoffroy, Fabricius, Burmeister, Curtis, Bouché, Guérin, and Percheron (Genera d. Ins. ), &c.